Nest Labs is set to share some user information with corporate parent Google for the first time since its February acquisition.

Matt Rogers, a co-founder of the smart-thermostat maker, said in an interview that Google will connect some of its apps to Nest, allowing Google to know when Nest users are at home or not.

The integration will allow those users to set the temperature of their homes with voice commands to a Google mobile app. It will also allow Google’s personal digital assistant, Google Now, to set the temperature automatically when it detects, using a smartphone’s location-tracking abilities, that a user is returning home.

Users will have to opt in for their information to be shared with Google, Rogers said. “We’re not becoming part of the greater Google machine,” he said.

The news comes as Nest said it will allow developers of appliances, light fixtures, garage door openers and more to access user information, part of Nest’s bid to be the operating system for the smart home.

The data sharing, particularly with Google, raises questions about user privacy. “What will happen to all this data? That is something that Google and Nest will have to be careful about,” said Gartner analyst Brian Blau. “There’s a higher expectation of privacy when you are in your home.”

Rogers tried to ease concerns when Google announced the Nest acquisition in January. “Our privacy policy clearly limits the use of customer information to providing and improving Nest’s products and services. We’ve always taken privacy seriously and this will not change,” he wrote in a blog post.

Most of the data that Nest will share – with Google and others – will focus on whether users are at home or not, as detected by sensors on the thermostat.
When people link a home device and related account with Nest, the company will not share their email address, name or home address with other companies, Rogers said.

Each company linking to Nest, including Google, will have to write to users explaining what data they are using and how they will use the information, Rogers said. There will also be a way to un-link the devices from Nest with one click through its mobile app, he added.

The integration with Google will be like “any other third party,” said Rogers.

Nest said Friday it would buy video-surveillance startup Dropcam for $555 million, bringing under Google’s umbrella sensitive real-time video of what is happening inside the homes of Dropcam users.

Privacy watchdogs are reserving judgment about Nest’s move to share information with Google.

Justin Brookman, director of consumer privacy at the Center for Democracy and Technology, said much will depend on how well Nest communicates to users what information they would be sharing.

“People should be in control of their own information,” he said. If Nest users are properly informed and opt-in, Brookman said he wouldn’t be as concerned about the potential violation of privacy.

It isn’t clear if Google would be capturing much new information about users. Its popular Google Maps app can already determine where users live and work based on where they carry their phones.

“We’re not telling Google anything that it doesn’t already know,” said Rogers.